Effects of losartan,an angiotensin II type 1 receptor antagonist,on experimental pulmonary fibrosis in rats

Objective To investigate the effects of losartan on bleomycin-induced pulmonary fibrosis in rats and its possible mechanism.Methods Forty-five male SD rats were randomly divided into three groups (n=15 in each group),ie. bleomycin group(intratracheal injected with bleomycin),losartan group(intratracheal injected with bleomycin and feed with losartan via a gastric tube),and control group.The rats were sacrificed 7,14 and 21 days after the treatment.Lung weights were measured and lung tissues were observed by haematoxylin and eosin stain.The expression of type Ⅰ collagen in the lung was examined by immunohistochemistry.The levels of interleukin-8(IL-8) and transforming growth factor-β_1(TGF-β_1) in bronchoalveolar lavage fluid(BALF) were assayed by enzyme-linked immunosorbent analysis.Neutrophils in BALF were also counted.Results The expression of type Ⅰ collagen in lung was reduced and the increase of neutrophils in BALF was significantly inhibited by losartan.Overexpression of TGF-β_1 in BALF on day 7 induced by bleomycin was also suppressed significantly by losartan.Conclusions The pulmonary fibrosis induced by bleomycin could be inhibited by losartan to some extent.The inhibitory effect of losartan may be ascribed to the reduction of TGF-β_1 partly.